1. Field of the Invention
The present invention relates to fluid cooling pipes for the use of fuel pipes, oil pipes and the like, EGR gas cooling apparatuses, air-conditions for adjusting temperature and humidity of room spaces, and other heat exchangers for vehicles or general industrial applications. Purpose of the present invention is to obtain a heat exchanger excellent in heat exchanging ability with a simple manufacturing technique and process at low cost.
2. Description of Related Art
Conventionally, there has been existing fluid cooling pipes for the use of fuel pipes, oil pipes and the like, EGR gas cooling apparatuses, air-conditions for adjusting temperature and humidity of room spaces, and other heat exchangers for vehicles or for the sake of general industrial applications. For example, a fuel pipe for vehicles, as shown in Japanese Patent Laying-Open No. 2001-200765, is connected to a fuel cooler comprising a tank for storing cooling water, coolant for air-conditions for vehicles and other coolant fluid to cool down oil or the like that flows within the fuel pipe. However, in the use of diesel engines, since the fuel pipes are placed on an underfloor, placement of tanks or the like to the underfloor where there is only a narrow space involves difficulties, and therefore there is a difficulty in realizing cooling by coolant fluid. In this regard, such air-cooling type heat exchangers have been frequently used that cooling is done by exchanging heat with the external air, as disclosed in Japanese Patent Laying-Open Nos. 09-42573, 2002-364476, 2003-88924 and 2002-64170.
Japanese Patent Laying-Open Nos. 09-42573 and 2002-364476 disclose that metal-made band-like fin members are disposed spirally on an outer periphery of a pipe main body and plate-like fin members are disposed radially, respectively. Japanese Patent Laying-Open No. 2003-88924 discloses that a plurality of straight pipe sections are inserted into a plurality of metal-made, e.g. aluminium, thin fins, mandrels are press-inserted into the pipe main bodies and straight pipe sections are expanded in order to caulk the fin members on the outer periphery of straight pipe sections. Then, adjacent ends of straight pipe sections are joined through an U-bend pipe to lengthen the entire pipe body in order to improve heat exchange ability.
In the above Japanese Patent Laying-Open Nos. 09-42573, 2002-364476, 2003-88924 and 2002-64170, there is disclosed that heat from oil or the like flowing within the pipe main body is discharged to the external air through the fin member, thereby cooling the oil. A heat exchanger using thin plate fins as disclosed in Japanese Patent Laying-Open No. 2003-88924 is widely used not only for fuel pipes but also for radiators, indoor equipment for air-conditions.
Japanese Patent Laying-Open No. 2002-64170 discloses a heat sink for cooling semiconductors and the like used in electronic devices such as computers, in which a plurality of fins are projectingly formed thereon by aluminium die casting to enhance heat discharge ability of the heat sink. Such a heat exchanger has been existing that the outer periphery of the fuel pipes, the oil pipes and the like are provided with a plurality of projecting fins by the aluminium die casting.